Kwave allows you to select a continuous range of samples as well as any combination of channels (if you edit a multi-channel file). By selecting a range of samples (time scope) all following commands will be limited to that range and by de-selecting a channel it's content will not be changed.
Selecting or de-selecting a channel is quite simple. Just click on the lamp symbol on the left side of the signal to toggle it's state:
a green lamp means "enabled", whereas
a red lamp means "disabled".
Note: If a channel is de-selected it will also not be audible for playback!
If you select a range of samples in Kwave, that range will be inclusive. That means that the first and the last selected sample both belong to the selection and will be used for the following actions. So even if you not selected a range but only a single sample, the selection will never be really "empty". So for example if you see no selected range, the "delete" function applies to that single sample.
The easiest way of selecting a range of samples is just to do that with mouse. It works like you are used from other applications: just press the left mouse button at the point you want to let the selection start and release the button where you want it to end.
If you want to adjust or move the selection's start or end, you can move the mouse cursor near to the start or the end of the selection until it changes from the standard arrow cursor into the left-right arrow cursor and then press the left mouse button and adjust.
You can also extend or shrink the selection to a specific point by holding down the shift button while klicking with the left mouse button. Depending on which border is nearer, the left or right border of the selection will be set to a new position.
There are also some functions available via the menu and of course some keyboard shortcuts:
select the whole signal: → → (Ctrl+A)
remove any selection and select "nothing": → → (N)
the currently visible area: → → (V)
the next block of samples, starting one sample after the end of the current selection and with the same length: → → (Shift++)
(Hint: use the "+" key from the numeric keypad!)
the previous block of samples, ending one sample before the start of the current selection and with the same length: → → (Shift+-)
(Hint: use the "-" key from the numeric keypad!)
expand the selection to the start of the signal (first sample): → → (Shift+Home)
expand the selection to the end of the signal (last sample): → → (Shift+End)
expand the current selection left and right up to the next label (or start/end of the signal if there is none), starting at the current cursor position: → → (E)
select the area between the next two labels that are right from the current selection or up to the end of the signal: → → (Shift+Ctrl+N)
select the area between the previous two labels that are left from the current selection or up to the start of the signal: → → (Shift+Ctrl+P)